Re: [web-devel] [hamlet] implicit spaces with newlines?

On Tue, May 24, 2011 at 4:13 PM, Michael Snoyman wrote:

On Tue, May 24, 2011 at 7:00 AM, Greg Weber wrote:

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The Yesod homepage looks like this:         <p>             If you are new to Yesod, you should start off with #             <a href=@{FiveMinutesR}>the five minute start instructions             . The #             <a href=@{ScreencastsR}>screencasts             \ give a nice introduction to some of the advanced concepts, and #             <a href=@{BookR}>the book             \ is the recommended approach to learning Yesod. Ask the #             <a href=@{CommunityR}>commnunity             \ for help. Allowing one-line tags in positions other than the very beginning allows for the removal of the '#' character:         <p>             If you are new to Yesod, you should start off with             \ <a href=@{FiveMinutesR}>the five minute start instructions             . The <a href=@{ScreencastsR}>screencasts             \ give a nice introduction to some of the advanced concepts, and             \ <a href=@{BookR}>the book             \ is the recommended approach to learning Yesod. Ask the             \ <a href=@{CommunityR}>commnunity             \ for help. Having implicit spaces is actually a huge win here:         <p>             If you are new to Yesod, you should start off with             <a href=@{FiveMinutesR}>the five minute start instructions             The             <a href=@{ScreencastsR}>screencasts             give a nice introduction to some of the advanced concepts, and             <a href=@{BookR}>the book             is the recommended approach to learning Yesod. Ask the             <a href=@{CommunityR}>commnunity             for help. But I am wondering if it is best to keep things the way they are but just indicate when there should be implicit spaces. My thought is to somehow use angle brackets. Changing <p> to <p>> would indicate implicit spaces.

What's the advantage of adding a new syntax for "implicit" space versus just explicitly adding the space?

I think he means that the child nodes of <p>> would be affected by some implicit spacing rules. Personally I prefer one consistent behaviour (explicit spacing every time). Trying to get too smart will get confusing and inaccurate quickly.

Michael

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Greg Weber On Fri, May 20, 2011 at 8:22 AM, Patrick Brisbin wrote:

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On 05/20/11 at 11:12am, Daniel Patterson wrote:

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I think what the original author was saying was that when you make a new line with html, whitespace is inserted, not whether hamlet should automatically insert space after every tag.

So yes, writing <p>hello<strong>there</strong></p> should not put white spacing.

But when you write, in html: <p>hello     <strong>there</strong></p>

It is equivalent to <p>hello <strong>there</strong></p> (note the space).

Isn't that simply due to the fact that HTML compresses whitespace across the board? (turning that "\n\t" or "\n    " into just " ")

Leading spaces in hamlet are used to define nesting, so also compressing this whitespace (rather than stripping it) would produce odd effects:

 <div>      <p>Hey          <strong>there

Would turn into

 <div> <p>Hey <strong>there</strong></p></div>

Which has an unneeded space after the parent <div>

Right?

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On May 19, 2011, at 11:57 PM, Michael Snoyman wrote:

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On Thu, May 19, 2011 at 11:49 PM, Patrick Palka wrote:

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I find it a bit unintuitive that the hamlet code

<p>hello    <strong>there

or

<p>     hello     <strong>there

generates the html

<p>hello<strong>there</strong></p>

I expected there to be a space between "hello" and "there" similar to what the html specifications dictate. Is this behavior intentional or an oversight? If it's the former, then what is the recommended way to simulate my expected behavior? Appending a space to the end of a line is mentally ugly and syntactically obscure.

I'm not sure what you mean by "what the html specifications dictate." HTML is whitespace-sensitive, meaning that:

  <i>foo</i> <b>bar</b>

and

   <i>foo</i><b>bar</b>

Are different. Now, in all likelihood in the above example, you will want to have the whitespace surrounding tags. But consider the following HTML:

   <p>You are logged in as <i>Michael Snoyman</i>, <a href="/logout">logout</a>.</p><p>Another paragraph.</p>

In the case of the <i> and <a> tags, we definitely do *not* want to add whitespace after the tag (though we do want it before the tag). In the case of <p>, we don't care one way or another, but adding the whitespace everywhere will take up (a trivial amount of) extra bandwidth. tl;dr: Sometimes you don't want the whitespace.

So when designing Hamlet, I thought up a few possibilities:

1) What we do now: all whitespace must be explicit. 2) Implicitly add whitespace before/after every tag. 3) Do something "smart", adding whitespace where it's desired.

(2) isn't really an option because it makes having a tag as the last word in a sentence impossible. (3) gives me the creeps: I like smart libraries, but I will *never* trust a library to do this kind of stuff correctly all the time, even if I'm the one making up the rules for it to follow! And I have no doubt that it will quickly devolve into 500 lines of hairy code to try and cover millions of corner cases. Oh, and don't forget that there are other languages than English that might approach it differently.

I suppose another possibility is (2) along with some special way of forcing the removal of extra whitespace, but this seemed much less intuitive than the current approach.

Anyway, that's the reasoning behind this stuff, if people have better ideas, I'd like to hear them.

Michael

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